The present invention is drawn to a switch or boost regulator apparatus and a method of operating the switching regulator apparatus, in which the switching regulator has a setting member or controllable electronic switch means which is controlled by a pulse width modulator, the pulse width modulator receiving a sawtooth-shaped signal having an approximately constant maximum amplitude and a signal dependent upon the current through the switching regulator inductance.
A switching regulator in which there is combined control of the setting member or controllable electronic switch means in dependence on a sawtooth-shaped signal and a switch current proportional signal is disclosed in German Patent No. DE-2,920,166.C2. Such a switching regulator has high stability, particularly against the tendency to oscillate even in cases in which its keying ratio (switch conductive period to OFF period) is more than one-half of a period of the switching frequency in duration.
It is known to change the keying ratio (on-to-off duration ratio) as a function of a switching regulator in that the amplitude of a sawtooth-shaped signal is changed in dependence on the magnitude of the input voltage as shown in the publication "Schaltnetzteile--Motorensteuerungen" [Switching Network Components--Motor Controls], published by Dr. Alfred Huthig Verlag, Heidelberg, 1982, at pages 101-102. However, this publication does not provide a suggestion as to how to operate a switching regulator to optimally suppress a noise voltage in the input voltage.
For example, a problem with the prior art switch controllers can occur due to the presence of alternating components in the otherwise steady input voltage of the switch controller, particularly CS noise (conducted susceptibility), which can adversely affect the operation of the switching regulator.